millivoltmeter B3-52/1.
The V3-52/1 digital millivoltmeter is designed to measure AC voltage from 1 mV to 3 V in the frequency range of 10 kHz to 1000 MHz (with an external divider, from 3 to 300 V in the frequency range of 100 kHz to 300 MHz). It features a digital display. The readings correspond to the root mean square (RMS) value of a sinusoidal voltage. It also has an AC-to-DC converter.
Source: QRZ.RU https://www.qrz.ru/schemes/detail/741...